A few weeks ago I read a news article about the miraculous reactivation of LES1, this satellite was built by the Massachusetts Institute of Technology and launched back in 1965. The satellite failed to reach its intended orbit owing to a wiring error and has been drifting out of control ever since, it was abandoned in 1967 as a piece of space junk but has seemingly begun transmitting again after 46 years.
Back in December Phil Williams G3YPQ from Cornwall noticed a peculiar signal and after some research determined it was LES1. The odd signal is probably caused by the satellite tumbling end over end every 4 seconds as the solar panels become shadowed by the engine. ‘This gives the signal a particularly ghostly sound as the voltage from the solar panels fluctuates’ Phil says. It is likely that the on board batteries have now disintegrated and some other component failure has caused the transmitter on 237Mhz, to start up when its in sunlight.
Eager to see if I could receive this ancient satellite I dug out an unused DAB 3-element antenna and mounted it on a tripod and successfully monitored two passes this afternoon.
I used my FUNCube Dongle (original version) and SDR-Radio V1.5 and this was the analysis of the resulting recorded IQ file for the pass that started around 17:30pm. You can clearly see the satellite signal as it undergoes Doppler shift and the four second regular frequency shift caused by the tumbling.
At its most northerly latitude the satellite orbit passes over North Africa, but due to its height has a longer orbit period than most other satellites and is receivable over much of Europe. How long it keeps transmitting is a mystery.
Had an excellent FITSAT-1 pass last night, successfully received nearly three full frames of CW telemetry.
The image above (from the heavens-above.com prediction site) shows a similar pass and illustrates the reception window which is just less than 8 minutes. Each frame of telemetry takes around 2.5 minutes to receive, so I was extremely happy with the results.
Again I recorded the pass using SDR-Radio and played back the doppler corrected IQ file later decoding with the MRP40 program, hear is a small video demonstrating the decoding process.
and this was the resulting telemetry data when run through the analyser program (see previous post).
--------------------------------------- FITSAT-1 NIWAKA Downlink CW Code --------------------------------------- Input Data------------------ S1 :f00501bb S2 :88db0101 S3 :02000102 S4 :1e20201f S5 :1a12aae7 -------S1------ S-mater of 437MHz RX :4.69[V] Total Voltage of Solar cells :0.1[V] Total Current of Solar Cells :0[mA] Voltage of single cell battery :3.65[V] -------S2------ Current of single cell battery :1054.69[mA] Voltage of 3 series battery :12.83[V] Current of 3 series battery :0[mA] Voltage of 2.5V reference :0.02[V] -------S3------ Voltage of Solar cell + X :0.07[V] Voltage of Solar cell + Y :0[V] Voltage of Solar cell - X :0.04[V] Voltage of Solar cell - Y :0.07[V] -------S4------ Temperature of 3 series battery :2.73[℃] Temperature of single cell battery :6.25[℃] Temperature of +Z side :6.25[℃] Temperature of –Z side :4.49[℃] -------S5------ S-meter of 1.2GHz RX :0.46[V] ------Timestamp----- 14day 3hour 49min 59sec
I have also uploaded a better recording of the audio.
Due to work and family commitments and the currently inconvenient timing of the passes I really haven’t had a serious attempt at receiving any of the downlinks from the numerous Cubesats launched on the Vega rocket back on Monday February 13.
I have managed to get some faint transmissions from what I believe is Masat-1 which has now been officially designated MagyarSat-OSCAR-72 (MO-72) I have also seen a number of other traces on the waterfall display of the sdr (using the FUNCube dongle) They are in the correct frequency range and appear and disappear as the cluster of cubesats were predicted as passing overhead.
I have managed to make a video of a pass of the SSB VO52(HAMSAT) downlink being received by the FCD this morning using just the antenna in the loft.
Operating a camera in one hand and trying to track the signal isn’t that easy, but you get the idea!
I have got a chance this weekend to have a proper attempt at the Vega cubesats.
Given the excellent positioning of the moon in the evening sky over the next few days I have been attempting some more decoding of weak signal EME (Earth-Moon-Earth) transmissions using my loft mounted homebrew wideband antenna, FUNCube dongle and SDR-Radio coupled with the MAP65-IQ application.
As you can see from last nights log, I had some success with this fairly rudimentary equipment, getting a reasonable number of decodes in a short space of time.
The only problem is at the moment is an annoying source of interference that keeps popping up across the band!
I have struggled repeatedly monitoring 2 meter amateur radio (144-146Mhz) with my various receivers due to noise and now the FCD watefall display has illustrated exactly how bad it is.
Here is a small video capture of the waterfall display this evening across the 2 meter EME band (no sound)
This QRM ‘splatter’ is intermittent and when present slowly moves up and down the band. I suspect this might possibly be interference from someone using an evil PLT device (more details at http://www.rsgb.org/emc/the-rsgb-and-ofcom.php) but it could be something more mundane.
I have discovered my own router/access point generate a number of signals (the two distinct bands either end of the waterfall display in that video are from the router) but the source of the more annoying splatter is as yet unidentified.
